A dust separating apparatus draws in air and separates any dust from the air. The term “dust” will be used herein to collectively refer to dust, dirt, particulates, and other similar materials. Dust separating apparatuses generally comprise one cyclone unit, such as disclosed in U.S. Pat. No. 964,428 to Johnson et al. Multi-cyclone units separate finer dust to improve dust collecting efficiency, and examples thereof can be found in GB344421; U.S. Pat. No. 2,553,175 to Davenport et al.; and U.S. Pat. No. 3,682,302 to Bernutat.
Multi-cyclone units are typically used for industrial cleaners, however, and not for home use because of its large volume. Accordingly, dust separating apparatuses have been developed, which can provide improved dust collecting efficiency and which are compact enough to be mounted in a small sized vacuum cleaner. For example, in Korean Patent Publication No. 437156, which is related to U.S. Pat. No. 6,546,593 to Oh et al., the inventor of the present invention discloses two cyclone units connected in series on the same plane so that a first cyclone unit encloses a second cyclone unit and therefore decreases the size of the dust separating apparatus. The disclosed arrangement of cyclone units is compact and can be applied to a vacuum cleaner for home use. Also, cyclone units in series provide improved dust collecting efficiency by collecting dust in two stages. Also, as described in WO 02/067753, a multi-cyclone dust separating apparatus to improve dust collecting efficiency comprises a first cyclone unit and a plurality of second cyclone units which are connected in parallel. Large dust is separated in the first cyclone unit, and fine dust is separated in the plurality of second cyclone units.
However, the volume and height of these conventional dust separating apparatuses are still relatively large. The conventional apparatuses can be generally applied to a large-sized upright vacuum cleaner but cannot be applied to a canister type vacuum cleaner. The conventional dust separating apparatuses comprise a plurality of cyclone units, but the plurality of cyclone units are difficult to arrange in series beyond three stages, without compromising compactness. Additionally, to empty the conventional dust collecting apparatus, the entire apparatus must be moved which inconveniences the user.